Securely joining one tissue portion to another is important to the successful treatment of various medical ailments. However, because tissue is soft, pliable, and moist and is often subject to dynamic movement, it can be difficult to maintain different segments of tissue joined together. Common methods for joining tissue segments together include: suturing with surgical thread secured by a surgical knot, lock device or application of surgical staples. The success of knotted sutures is dependent on the skill of the physician forming a strong surgical knot. Both stapling and suturing are susceptible to failure if the tissue surrounding the suture or staple tears permitting the material to break free and release the tissue.
Another method for retaining segments of tissue together involves the application of adhesive. Adhesives may be applied in connection with a reinforcing substrate that is flexible, such as a bandage or flexible strip. Alternatively, the adhesive may be applied directly to the tissue folds. Biologically safe tissue adhesives are sometimes used in surgical applications to help maintain tissues joined together. However, the moist pliable nature of tissue makes successfully bonding tissue surfaces together difficult. The bonding agent may not adhere to the tissue surface in the presence of biological fluids, etc. Additionally, the dynamic environments in which most tissue areas exist tend to weaken bonds created by adhesives.
Adhering tissue layers together can be challenging in both external treatment sites as well as internal treatment locations. Internally located tissues may be more difficult to bond together because they are more remote and difficult to reach for securement methods, such as suture placement and knot tying. Additionally, internal treatment sites may be exposed to a moist environment of body fluids such as blood or harsh corrosive substances contained within the body that may serve to weaken adhesive bonds or restraining means such as suture or staples.
Joining tissue can be especially challenging in endoscopic tissue apposition procedures. Endoscopic tissue apposition devices are available that can be used in the body of a patient without the need to make an external incision in the patient, the device being controlled externally of the patient by endoscopic means. The device may comprise a sewing or stapling device for use in flexible endoscopy, though it is also applicable to devices for use in rigid endoscopy.
Apposition devices of this general type are described in, for example, U.S. Pat. Nos. 5,080,663 and 5,792,153. Those patents disclose a sewing device for passing a suture thread through a tissue fold, which comprises a hollow needle movable between a first position in which it is out of the said tissue fold and a second position in which it passes through the said tissue fold, and a thread carrier adapted to be attached to the thread and being receivable within the hollow needle. The sewing device comprises a body, which defines a cavity within which the tissue fold can be held by means of suction, and the hollow needle is mounted for movement in the body between the first and second positions.
Two particular embodiments are described in the above-referenced U.S. Pat. No. 5,792,153 patent: a single stitch sewing device, and a multiple stitch sewing device. In the single stitch device, the thread carrier is transported by the needle through the tissue as the latter passes from its first position to its second position. When the needle returns to its first position, the thread carrier is left behind in the distal end of the sewing capsule. In the multiple stitch device, the same procedure occurs, but it is followed by a further step in which the hollow needle travels from its first position to its second position, picks up the thread carrier, and returns it. A second stitch may be formed during the next step. The whole sequence of steps is repeated as many times as may be required to form the desired number of stitches.
A variable in the success of keeping tissue joined together is the quality of the surgical knot tied to secure the tissue. It would be desirable to improve the reliability of the suture knot to increase the level of confidence in the procedures performed using the above-mentioned endoscopic devices. To improve the reliability of known methods of securing tissue together, the methods should be improved, or safeguarded with a secondary securement operation. The present invention provides improved methods and devices for joining tissue.